Considerable efforts are being made toward finding a compound which will effectively inhibit the replication of retroviruses and in particular to inhibit HIV replication. In order to be useful in treating an individual infected with HIV the compound would be required to inhibit HIV replication while not being fatally toxic to normal cells.
The present inventors noted the relationship between CD8.sup.+ cell anti-HIV activity and the clinical condition of an individual infected with HIV. Mackewicz, C. E. et al., CD8.sup.+ cell anti-HIV activity correlates with the clinical state of the infected individual, J. Clin. Invest. 87, 1462-1466, 1991. With this relationship in mind efforts were made to extract from CD8.sup.+ cells a component which is capable of inhibiting HIV replication. Others have studied CD8.sup.+ cells and the effects of such cells on viral replications. For example see Brinchmann et al., "CD8.sup.+ T Cells Inhibit HIV Replication in Naturally Infected CD4.sup.+ T Cells," Journal of Immunology (1990) 144:2961-2966; Walker et al., "CD8.sup.+ Lymphocytes Can Control HIV Infection In Vitro by Suppressing Virus Replication," Science (1986) 234:1563-1566; Walker et al., "A diffusible lymphokine produced by CD8.sup.+ T lymphocytes suppresses HIV replication," Immunology (1989) 66:628-630.
Brinchmann et al. teach placing the CD8+ cells in proximity to cells infected with HIV. Based thereon, Brinchmann et al. speculated that some factor or factors are excreted from the CD8+ cells which inhibits HIV proliferation. There is no disclosure or attempt made with respect to: (1) isolating what that factor(s) might be; (2) determining if a single factor was responsible as opposed to a number of different compounds being excreted by the CD8+ cells; or (3) determining if such factor(s) are different from factors known at the time.
The two Walker et al. publications do not isolate and characterize such a factor and do not indicate that a specific factor, different from other known factors, is responsible for inhibiting HIV replication.
Although others have noted a relationship between CD8.sup.+ cells and HIV replication, they have not isolated any single protein extractable from the cells which could be shown as the basis for antiviral activity. The present inventors have isolated and characterized such a protein.